Combined sealing element, manufacturing method thereof and sealing structure

Abstract

The invention belongs to the technical field of sealing, and particularly relates to a combined sealing piece, a manufacturing method thereof and a sealing structure. The combined sealing piece comprises a first supporting ring, a second supporting ring, a first graphite ring, a second graphite ring and an alloy ring. The first graphite ring and the second graphite ring are constructed to be capable of conducting sealing operation on the first sealing face and the second sealing face correspondingly, and the alloy ring is constructed to be capable of being melted in response to temperature rising, so that radial acting force on the first graphite ring and the second graphite ring is generated under axial extrusion of the first supporting ring and the second supporting ring; therefore, the sealing effect on the first sealing surface and the second sealing surface is enhanced. According to the combined sealing element, the related requirements for sealing in the high-temperature and high-pressure environment can be met, the combined sealing element can be further suitable for low-speed dynamic sealing occasions, and the combined sealing element has good application prospects in the technical field.

Description

Technical Field

[0001] The invention belongs to the technical field of sealing, and in particular relates to a combined sealing component and a manufacturing method and a sealing structure thereof. Background Art

[0002] With the in-depth development of unconventional oil and gas resources, geological conditions and construction conditions are becoming more and more complex, and the sealing requirements for downhole testing and operating tools are becoming higher and higher. Under extreme conditions, the downhole temperature can reach 350°C or even higher, and the sealing pressure is often also high, reaching 50MPa or higher. The sealing problem under high temperature and high pressure conditions has not been well solved.

[0003] Most of the existing seals are based on rubber elements, but the long-term stable working temperature of rubber element seals is limited. Even the perfluororubber with the best temperature resistance currently has a long-term stable working temperature of less than 300°C, so it cannot adapt to higher working environment temperatures.

[0004] Various sealing methods based on all-metal sealing elements (such as O- and C-shaped metal rings) can withstand high temperatures, but due to the poor resilience of metal seals, sealing requires a large excitation force. In order to ensure reliable sealing, the processing and installation accuracy of metal sealing elements and structures are very high. At the same time, the contact stress and contact surface wear of metal-to-metal sealing surfaces are a pair of difficult-to-solve contradictions. After the contact surface is worn, it is difficult to compensate, resulting in easy failure of the seal. Therefore, metal seals are usually only used in static sealing occasions. Summary of the invention

[0005] In view of some or all of the problems existing in the prior art, the present invention provides a combined seal, a manufacturing method thereof and a sealing structure.

[0006] According to a first aspect of the present invention, a combined seal is provided.

[0007] The combined seal comprises:

[0008] A first supporting ring, comprising a first main body and a first protrusion disposed on a lower surface of the first main body;

[0009] A second supporting ring, comprising a second main body, and a second protruding portion disposed on an upper surface of the second main body and opposite to the first protruding portion;

[0010] A first graphite ring, disposed outside the first protrusion and the second protrusion;

[0011] a second graphite ring, disposed inside the first protrusion and the second protrusion; and

[0012] The alloy ring is filled in the area surrounded by the first protrusion, the second protrusion, the first graphite ring and the second graphite ring.

[0013] The first graphite ring and the second graphite ring are configured to respectively perform sealing operations on the first sealing surface and the second sealing surface, and the alloy ring is configured to melt in response to an increase in temperature, thereby generating radial forces on the first graphite ring and the second graphite ring under axial extrusion of the first support ring and the second support ring, thereby enhancing the sealing effect on the first sealing surface and the second sealing surface.

[0014] As an extension of the above technical solution, the present invention also provides the following embodiments:

[0015] The first graphite ring and the second graphite ring are made of expanded graphite.

[0016] The density of the first graphite ring and the second graphite ring is in the range of 1.4-1.6 g / cm3.

[0017] The first support ring and the second support ring are configured such that, at the highest operating temperature, their outer diameters are at least 0.1 mm smaller than the inner diameter of the first sealing surface, and their inner diameters are at least 0.1 mm larger than the outer diameter of the second sealing surface.

[0018] The hardness of the first support ring and the second support ring is 50-100 HB lower than the hardness of the first sealing surface and the second sealing surface.

[0019] The melting point of the alloy ring is between 45°C and 70°C.

[0020] The alloy ring is made of tin-bismuth alloy or indium-tin-bismuth alloy.

[0021] According to a second aspect of the present invention, a method for manufacturing a combined sealing element is provided.

[0022] The manufacturing method of the combined seal comprises the following steps:

[0023] 1) providing the first graphite ring and the second graphite ring;

[0024] 2) providing the first support ring and the second support ring;

[0025] 3) pressing the first graphite ring and the second graphite ring into the first support ring / the second support ring;

[0026] 4) heating the alloy material to a molten state, and injecting the alloy material into the cavity formed by the first graphite ring, the second graphite ring, and the first support ring / the second support ring;

[0027] 5) pressing the second support ring / the first support ring into the alloy ring before the alloy material solidifies into the alloy ring;

[0028] 6) Keeping the second support ring / the first support ring under pressure for no less than half an hour.

[0029] According to a third aspect of the present invention, a sealing structure is provided.

[0030] The sealing structure comprises:

[0031] Not less than two combined seals as described above;

[0032] A butterfly spring disposed between two adjacent combined seals; and

[0033] A locking ring connected to the first sealing member / the second sealing member and abutting against the uppermost combined sealing member and applying a pre-tightening force to the uppermost combined sealing member.

[0034] As an extension of the above technical solution, the present invention also provides the following embodiments:

[0035] The disc spring is configured such that its outer diameter is at least 0.5 mm smaller than the inner diameter of the first sealing surface, and its inner diameter is at least 0.5 mm larger than the outer diameter of the second sealing surface.

[0036] The advantages of the present invention compared to the prior art are:

[0037] (1) Compared with the rubber sealing method, the combined seal according to the present invention is made of graphite material and metal material, can withstand temperatures of 350°C or higher for a long time, can be suitable for sealing requirements in high-temperature working environments, and the sealing pressure can reach 50MPa or above.

[0038] (2) Compared with metal sealing, the graphite material in the combined seal according to the present invention has higher compression resilience and smaller stress relaxation rate, and also has good self-lubricating property. When used with butterfly spring, it can not only be used for static sealing under high temperature and high pressure environment, but also can adapt to low speed dynamic sealing occasions, and the wear on the sealing surface is very small.

[0039] (3) The graphite material in the combined seal and sealing structure according to the present invention has excellent corrosion resistance, radiation resistance and thermal stability, and can be adapted to the sealing of a variety of fluid media. Its application range is wider than that of metal seals.

[0040] (4) The combined seal and sealing structure according to the present invention have lower requirements on the processing and installation accuracy of the sealing surface than metal seals, have lower sealing excitation force, and are more convenient and quick to install and use.

[0041] (5) The combined seal and the sealing structure according to the present invention have low cost of materials used, are simple in manufacturing method, and are suitable for mass production and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a structural schematic diagram of a sealing structure according to the present invention;

[0043] Figure 2 A schematic diagram of a partial structure of a combined seal according to the present invention;

[0044] Figure 3 It is a schematic diagram of the local structure of the butterfly spring according to the present invention.

[0045] All drawings in the present invention are schematic diagrams for illustrating structures and principles, and are not necessarily drawn according to actual sizes and proportions.

[0046] The specific meanings of the reference numerals in the figures are as follows:

[0047] 1. First support ring; 11. First main body; 12. First protrusion; 2. Second support ring; 21. Second main body; 22. Second protrusion; 3. First graphite ring; 4. Second graphite ring; 5. Alloy ring; 6. First sealing element; 61. First sealing surface; 7. Second sealing element; 71. Second sealing surface; 8. Butterfly spring; 9. Locking ring; 100. Combined seal; 200. Sealing structure. DETAILED DESCRIPTION

[0048] The embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

[0049] According to a first aspect of the present invention, a combined seal is provided.

[0050] like Figure 1 and Figure 2As shown, the combined seal 100 according to the present invention includes a first support ring 1, a second support ring 2, a first graphite ring 3, a second graphite ring 4 and an alloy ring 5. The first support ring 1 includes a first body 11 and a first protrusion 12 arranged on the lower surface of the first body 11. The second support ring 1 includes a second body 2 and a second protrusion 22 arranged on the upper surface of the second body 21 and opposite to the first protrusion 12. The first graphite ring 3 is arranged on the outside of the first protrusion 12 and the second protrusion 22, and the second graphite ring 4 is arranged on the inside of the first protrusion 12 and the second protrusion 22. The alloy ring 5 is filled in the area surrounded by the first protrusion 12, the second protrusion 22, the first graphite ring 3 and the second graphite ring 4. Furthermore, the first graphite ring 3 and the second graphite ring 4 are configured to respectively perform sealing operations on the first sealing surface 61 on the first sealing member 6 and the second sealing surface 71 on the second sealing member 7, and the alloy ring 5 is configured to melt in response to an increase in temperature, thereby generating radial forces on the first graphite ring 3 and the second graphite ring 4 under the axial extrusion of the first support ring 1 and the second support ring 2, thereby enhancing the sealing effect on the first sealing surface 61 and the second sealing surface 71.

[0051] Through this design, firstly, the combined seal 100 according to the present invention can be heat-resistant and sealed for a long time in an operating environment where the external temperature reaches 350°C or higher, and the sealing pressure can reach 50MPa or above, thereby meeting the sealing requirements under high temperature and high pressure working environment. Secondly, the graphite material in the combined seal 100 according to the present invention has good corrosion resistance, radiation resistance and thermal stability, and can be adapted to the sealing of a variety of fluid media, with a wider range of applications. Thirdly, the combined seal 100 according to the present invention has lower requirements on the processing and installation accuracy of the sealing surface than metal seals, has low sealing excitation force, and is more convenient and quick to install and use. Thirdly, the graphite material in the combined seal according to the present invention has higher compression resilience and lower stress relaxation rate, and also has good self-lubricating properties, which can be applied to low-speed dynamic sealing occasions, and causes little wear on the sealing surface. In addition, the material cost used in the combined seal 100 according to the present invention is low, and has good economy.

[0052] In one embodiment of the present invention, the first graphite ring 3 and the second graphite ring 4 are made of expanded graphite. In addition to the excellent properties of natural graphite such as resistance to cold and heat, corrosion resistance and self-lubrication, expanded graphite also has the characteristics of softness, high compression resilience and strong adsorption that natural graphite does not have. Using expanded graphite to make the first graphite ring 3 and the second graphite ring 4 fully utilizes its excellent properties and improves the sealing effect of the first seal 6 and the second seal 7.

[0053] Furthermore, in one embodiment of the present invention, the density of the first graphite ring 3 and the second graphite ring 4 is in the range of 1.4-1.6 g / cm3. This arrangement can maximize the characteristics of the expanded graphite, such as strong softness and high compression resilience, so that the combined seal according to the present invention can achieve the best sealing effect.

[0054] like Figure 1 As shown, in one embodiment of the present invention, the first support ring 1 and the second support ring 2 are constructed such that at the highest operating temperature, their outer diameters are at least 0.1 mm smaller than the inner diameter of the first sealing surface 61, and their inner diameters are at least 0.1 mm larger than the outer diameter of the second sealing surface 71. The installation gap can be calculated based on the thermal expansion coefficient of the materials used for the first support ring 1, the second support ring 2, the first seal 6 and the second seal 7, and the highest operating temperature. Through this design, it is possible to avoid the first support ring 1 and the second support ring 2 from scratching or even locking with the first sealing surface 61 and the second sealing surface 71 due to the thermal expansion effect at the highest operating temperature, thereby protecting the first sealing surface 61 and the second sealing surface 71, and also ensuring the independence of the combined seal 100, so that it can be used in working conditions requiring dynamic sealing.

[0055] In one embodiment of the present invention, the hardness of the first support ring 1 and the second support ring 2 are both 50-100 HB lower than the hardness of the first sealing surface 61 and the second sealing surface 71. With this design, while ensuring that the first support ring 1 and the second support ring 2 have sufficiently high strength and hardness, it also avoids possible scratches and damage to the first sealing surface 61 and the second sealing surface 71 when the first support ring 1 and the second support ring 2 contact with the first sealing surface 61 and the second sealing surface 71 during the installation process, thereby protecting the first sealing surface 61 and the second sealing surface 71.

[0056] Preferably, the first support ring 1 and the second support ring 2 are made of stainless steel or tin bronze materials.

[0057] Preferably, when the sealing medium is highly corrosive, the first support ring 1 and the second support ring 2 are made of Hastelloy as raw material.

[0058] In one embodiment of the present invention, the melting point of the alloy ring 5 is between 45 and 70°C. Through this arrangement, on the one hand, when manufacturing the combined seal 100, the first support ring 1 and the second support ring 2 can be connected as a whole through the alloy ring 5 without a very high temperature, so that the combined seal 100 can be easily formed into an integral structure, thereby facilitating the installation work of the construction personnel. On the other hand, during use, when the temperature rises, the alloy ring 5 can be easily melted into a liquid state and expand in volume. The liquid alloy material formed by the melting of the alloy ring 5 generates a radial force through the axial extrusion of the first support ring 1 and the second support ring 2 and acts on the first graphite ring 3 and the second graphite ring 4, thereby quickly playing a role in strengthening the sealing effect of the first sealing surface 61 and the second sealing surface 71.

[0059] Preferably, the alloy ring 5 is made of a tin-bismuth alloy or an indium-tin-bismuth alloy having a melting point of 45-70°C.

[0060] The combined seal 100 according to the present invention benefits from the composite use of graphite material and metal material. First, it can be sealed for a long time with temperature and pressure resistance in an operating environment where the external temperature reaches 350°C or higher and the sealing pressure reaches 50MPa or higher, thereby meeting the sealing requirements under high temperature and high pressure working environment. Secondly, the graphite material in the combined seal 100 according to the present invention has good corrosion resistance, radiation resistance and thermal stability, and can be adapted to the sealing of various fluid media, with a wider range of applications. Thirdly, the combined seal 100 according to the present invention has lower processing and installation accuracy requirements for the sealing surface than metal seals, and the installation and use are more convenient and quick, and the sealing excitation force is low. Thirdly, the graphite material in the combined seal according to the present invention has higher compression resilience and lower stress relaxation rate, and also has good self-lubricating property, which can be applied to low-speed dynamic sealing occasions, and the wear on the sealing surface is very small. In addition, the material cost used in the combined seal 100 according to the present invention is low, and it has good economy.

[0061] According to a second aspect of the present invention, a method for manufacturing a combined sealing element is provided.

[0062] The manufacturing method of the combined seal comprises the following steps:

[0063] 1) providing a first graphite ring 3 and a second graphite ring 4;

[0064] 2) providing a first support ring 1 and a second support ring 2;

[0065] 3) Pressing the first graphite ring 3 and the second graphite ring 4 into the first support ring 1 / the second support ring 2;

[0066] 4) heating the alloy material to a molten state, and injecting it into the cavity formed by the first graphite ring 3, the second graphite ring 4 and the first support ring 1 / the second support ring 2;

[0067] 5) Pressing the second support ring 2 / first support ring 1 into the alloy ring before the alloy material solidifies into the alloy ring;

[0068] 6) Keep the second support ring 2 / first support ring 1 under pressure for no less than half an hour.

[0069] In one embodiment of the present invention, the first graphite ring 3 and the second graphite ring 4 are provided in step 1) by pressing graphite through a mold, thereby manufacturing the required first graphite ring 3 and the second graphite ring 4.

[0070] In one embodiment of the present invention, the first support ring 1 and the second support ring 2 are provided in step 2) by machining the selected metal material to produce the required first support ring 1 and the second support ring 2 .

[0071] The manufacturing method of the combined seal according to the present invention has clear steps, is simple and easy to implement, and due to the setting of step 6), the yield is high, and is suitable for batch production of the combined seal 100 according to the present invention.

[0072] According to a third aspect of the present invention, a sealing structure 200 is provided.

[0073] like Figure 1 As shown, the sealing structure 200 according to the present invention comprises at least two combined seals 100 as described above, a butterfly spring 8 disposed between two adjacent combined seals 10, and a locking ring 9 connected to the first seal 6 / the second seal 7 and abutting against the uppermost combined seal 100 and applying a pre-tightening force to the uppermost combined seal 100.

[0074] During specific operation, the combined seal 100 is arranged between the first sealing surface 61 and the second sealing surface 71, a butterfly spring 8 is arranged between two adjacent combined seals 100, and a locking ring 9 is arranged above the uppermost combined seal 100, which is connected to the first seal 6 or the second seal 7 and can apply a pre-tightening force to the combined seal 100 in contact therewith. The pre-tightening force is transmitted downward to the combined seal 100 under the butterfly spring 8 through the butterfly spring 8 under the combined seal 100, and then transmitted downward to the combined seal 100 under the lowermost in turn, so that the sealing structure 200 can also play a sealing role on the first sealing surface 61 and the second sealing surface 71 in a normal temperature environment. When the sealing structure 200 is in a high-temperature operating environment, the alloy ring 5 in the combined seal 100 melts and expands in volume, and under the action of the axial force applied by the first support ring 1 and the second support ring 2, a radial force is generated on the first graphite ring 3 and the second graphite ring 4 on both sides thereof, thereby enhancing the sealing effect on the first sealing surface 61 and the second sealing surface 71.

[0075] According to the sealing structure 200 of the present invention, the combined seal 100, the butterfly spring 8 and the locking ring 9 are used in combination, and the structure is stable and reliable. It is not only suitable for static sealing in high temperature and high pressure environments (the external temperature reaches 350°C and above, and the sealing pressure reaches 50MPa and above), but also can adapt to low-speed dynamic sealing occasions, with little wear on the sealing surface, and has a relatively wide range of applications. Moreover, the sealing structure 200 has lower requirements on the processing and installation accuracy of the sealing surface than metal sealing, has a low sealing excitation force, and is more convenient and quick to install and use. In addition, since the sealing structure 200 includes the combined seal 100, the sealing structure 200 can also produce other technical effects that the combined seal 100 can produce, which will not be repeated here.

[0076] In one embodiment of the present invention, the butterfly spring 8 is constructed such that its outer diameter is at least 0.5 mm smaller than the inner diameter of the first sealing surface 61, and its inner diameter is at least 0.5 mm larger than the outer diameter of the second sealing surface 71. This design ensures that the butterfly spring 8 will not come into contact with the first sealing surface 61 and the second sealing surface 71 during the operation of the sealing structure 200, thereby maintaining the independence of the sealing structure 200, and while protecting the first sealing surface 61 and the second sealing surface 71, the sealing structure 200 can be smoothly applied to an operating environment with a dynamic sealing requirement.

[0077] In one embodiment of the present invention, in order to control the elastic force of the butterfly spring 8 within an appropriate range and ensure the smooth sealing effect of the sealing structure 200, the butterfly spring 8 is made of thin spring steel with a single sheet thickness of about 0.5-1mm and a compression stroke of about 1mm.

[0078] In one embodiment of the present invention, the sealing structure 200 includes three combined sealing elements 100 and two butterfly springs 8. This design can be applied to most sealing environments and can produce a good sealing effect.

[0079] In this application, the specific meanings of the terms "upper", "lower", "inner", "outer", "middle", "side" and the like when indicating directions are as follows: Figure 1 The drawing state of the middle sealing structure 200 is for reference.

[0080] Finally, it should be noted that although the present invention has been described in detail with reference to the preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A combined seal, comprising: A first supporting ring (1) comprises a first main body (11) and a first protruding portion (12) arranged on the lower surface of the first main body (11); A second supporting ring (2) comprises a second main body (21) and a second protruding portion (22) arranged on the upper surface of the second main body (21) and arranged opposite to the first protruding portion (12); A first graphite ring (3) is arranged outside the first protruding portion (12) and the second protruding portion (22); a second graphite ring (4) disposed inside the first protruding portion (12) and the second protruding portion (22); and The alloy ring (5) is filled in a region surrounded by the first protrusion (12), the second protrusion (22), the first graphite ring (3) and the second graphite ring (4). The first graphite ring (3) and the second graphite ring (4) are configured to respectively perform sealing operations on the first sealing surface (61) and the second sealing surface (71), and the alloy ring (5) is configured to melt in response to an increase in temperature, thereby generating a radial force on the first graphite ring (3) and the second graphite ring (4) under the axial compression of the first support ring (1) and the second support ring (2), thereby enhancing the sealing effect on the first sealing surface (61) and the second sealing surface (71).

2. The combined seal according to claim 1, characterized in that: The first graphite ring (3) and the second graphite ring (4) are made of expanded graphite.

3. The combined seal according to claim 2, characterized in that: The density of the first graphite ring (3) and the second graphite ring (4) is between 1.4 and 1.6 g / cm 3 within the range.

4. The combined seal according to claim 3, characterized in that: The first support ring (1) and the second support ring (2) are configured such that, at the highest operating temperature, their outer diameters are at least 0.1 mm smaller than the inner diameter of the first sealing surface (61), and their inner diameters are at least 0.1 mm larger than the outer diameter of the second sealing surface (71).

5. The combined seal according to claim 4, characterized in that: The hardness of the first support ring (1) and the second support ring (2) is 50-100 HB lower than the hardness of the first sealing surface (61) and the second sealing surface (71).

6. The combined seal according to any one of claims 1 to 5, characterized in that: The melting point temperature of the alloy ring (5) is between 45°C and 70°C.

7. The combined seal according to claim 6, characterized in that: The alloy ring (5) is made of tin-bismuth alloy or indium-tin-bismuth alloy.

8. A method for manufacturing a combined seal, comprising the following steps: 1) providing the first graphite ring (3) and the second graphite ring (4); 2) providing the first support ring (1) and the second support ring (2); 3) pressing the first graphite ring (3) and the second graphite ring (4) into the first support ring (1) / the second support ring (2); 4) heating the alloy material to a molten state, and injecting the alloy material into a cavity formed by the first graphite ring (3), the second graphite ring (4) and the first support ring (1) / the second support ring (2); 5) before the alloy material solidifies into the alloy ring (5), pressing the second support ring (2) / the first support ring (1); 6) Keeping the second support ring (2) / the first support ring (1) in a compressed state for no less than half an hour.

9. A sealing structure comprising: No less than two combined seals according to any one of claims 1 to 7; A butterfly spring (8) disposed between two adjacent combined sealing elements; as well as A locking ring (9) is connected to the first sealing member (6) / the second sealing member (7) and abuts against the uppermost combined sealing member and applies a pre-tightening force to the uppermost combined sealing member.

10. The sealing structure according to claim 9, characterized in that: The disc spring (8) is constructed such that its outer diameter is at least 0.5 mm smaller than the inner diameter of the first sealing surface (61), and its inner diameter is at least 0.5 mm larger than the outer diameter of the second sealing surface (71).

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